The present invention relates to a communication signal transport technology, in particular, it relates to a method and a system for transport signals over an Optical Transport Network (OTN).
In the early 1990s, transport network evolved from a PDH network into a SDH network, which provided a large capacity synchronous transmission platform for voice operation and data operation. Currently, SDH network is facing the challenge of transitioning to an Optical Transport network (OTN) mode. The OTN network, as opposed to the SDH network, provides a transparent transport channel unrelated to customer operations, in addition to the large-capacity, multi-level management, enhanced foreword error correction functions. With service providers gradually accepting and deploying the OTN network, service providers are demanding OTN networks to provide open interfaces and achieve OTN equipment butt joint for multiple equipment providers. The service providers have already made the butt joint capability of an equipment manufacturer a first priority.
In real world applications, in addition to the OTN butt joint interface requirement, it also needs to provide transparent transport capability of OTN signals. Particularly in a network environment where there are multiple equipment manufacturers and multiple service providers, the different management domains are not yet fully exchangeable at all levels, or a trust relationship has not been established between the management domains. Therefore, the industry urgently demands an OTN network middle management domain for providing OTN signal transparent transport capabilities.
As a current technology, the proposed document OTN G.709 reveals an OTU signal transparent transport technology. This technology directly terminates the overhead of the relevant Operation, Administration, Maintenance and Provision (OAM&P) (that is, OTUj OAM&P, abbreviated as the control overhead) at the 3R point (namely, the management domain boundary point). Then, maps or multiplexes ODUj to OTUk (j<=k) signals of another management domain, extracts the ODUj signal from the OTUk signals in the management domain where OTUk signals belong, then re-inserts the OAM&P overhead related to the OTUj signals, and regenerates OTUj signals. The generation and stopping of the OTUk control overhead of the aforementioned OTUk signals are the location for formation and suspension of the OTUk, and the OTUk control overhead is used for segment communication and monitoring processing. Therefore, processing an OTUk control overhead is needed for generation and termination of each OTUk signal.
However, the drawbacks for the current technology are: only the ODUj signal in OTUj signals can be transparently transported; the OTUj related control overhead can not be transparently transported; total transparent transport of the OTU signals through the OTN network can not be realized.